A slithery GT coupe powered by GM's 6.6-liter Duramax turbodiesel? What's next, a Navistar-powered TVR? A Cummins 610 Turbo Morgan? Not so fast — the Trident Iceni is for real. And with 375 hp and 520 lb-ft of torque, it can get up and go from zero to 60 mph in 3.9 seconds and top out at 170 mph. The company's taking orders on the six-figure sportster now. But before it does, it wants to prove the Iceni's fuel efficiency and eco-friendliness, so it's driving one of the cars from the UK to the Top Marques show in Monaco this week on a single tank of biodiesel. That's 900 miles on 26 gallons (and the filler will be sealed, so no clandestine fillups. Let's see a Duramax Silverado top that. – Mike Spinelli